1. ACIDS and BASES

2. Facts
For MANY years people have known that vinegar, lemon juice and many other foods taste sour.
It was not until a few hundred years ago that it was discovered why these things taste sour - because they are all acids.

3. ACIDS BASES taste sour, are corrosive to metals, change litmus red,
and become less acidic when mixed with bases
release hydrogen ions (H+) in water
Acids are electrolyte.
Strong acids destroy fabric.
Strong acids cause burn on skin.
feel slippery,
Taste bitter
change litmus blue,
and become less basic when mixed with acids
release hydroxide ions (OH-) in water
They conduct electricity

5. Acids: ~taste sour ~release hydrogen ions (H+) in water
~have a pH lower than 7 (1-6)
~the stronger the acid, the LOWER the number on the pH scale
~Ex. HCl (hydrochloric acid)

6. Bases ~taste bitter ~release hydroxide ions (OH-) in water
~have a pH HIGHER than 7 (8-14)
~the stronger the base, the HiGhER the number on the pH scale
~Ex. NaHCO3 (baking soda)

7. Neutralization- a chemical reaction that takes place when an acid combines with a base.
During this, a salt and water are formed.

8. Chemical and Physical Changes

9. Chemical Change
Change from one substance to another
Burning paper

10. Physical Change
Change is physical or outward appearance. Does not change chemical make-up
Wrinkled paper

11. Chemical Reactions Types
Endothermic-energy absorbed
Exothermic- energy is released